Stabilizer for drill collars and drill pipes



Nov. 19, 1957 K. H. SWART STABILIZER FOR DRILL COLLARS AND DRILL PIPESFiled June 15 1953 IN V EN TOR.

nrraeuws United States Patent STABILIZER FOR DRILL COLLARS AND DRILLPIPES Kenneth H. Swart, Whittier, Calif., assignor to SecurityEngineering Division, Dresser Operations, Inc., Whattier, Calil:., acorporation of California Application June 15, 1953, Serial No. 361,598

Claims. (Cl. 25528) The drill collars are in the form of thick-walledtubular members designed to supply the desired amount of weight on thebit and to afford sufiicient stifiness to cause the bit to drill in avertical direction despite deviating tendencies occasioned by variousstrata that are encountered. Despite the thick walls and the stiifnessof the drill collars, the flexibility of the drill collars is such-thatcoupled with the flexibility of the drill pipe, the lower portion of thedrilling string will tend to lean against a wall of the hole beingdrilled which affords an opportunity for the bit to deviate from thevertical.

It has heretofore been proposed to hold the drill collars and/or drillpipe centrally of the hole to avoid this deviation. In so doing, reamershave been incorporated in the drill string a short distance abovethesition thereon. The construction of such special drill collars madeup of two or more parts is objectionable not only from the standpoint ofexpense, but also from the standpoint of weakening the structure of thedrill collar.

An object of the present invention is to provide an improved stabilizerfor drill collars and/or drill pipes wherein the stabilizer is in theform of a split sleeve, the two parts of which can be mutually assembledtogether about a drill collar and locked in position there on. Thisenables a single-piece mandrel or drill collar to be employed which canbe of adequate strength. The construction is also advantageous in thatif a stabilizer becomes worn or damaged it may be disassembled andreplaced at the well drilling rig.

Another object of the invention is to provide a stabilizer having theabove-mentioned characteristics consisting of a single-piece mandrel ordrill collar which is externally reduced between shoulders and which hasthe stabilizer in the form of a split sleeve assembled thereabouts. Thisstabilizer has its parts in the form of a metallic reenforcement havingrubber disposed on the exterior and interior thereof and bonded thereto.The rubber has an external diameter substantially equal to the gaugediameter of the bit that is being used so that it will be capable ofholdingv the mandrel at substantially the center of the hole beingdrilled. It is externally fluted to provide for the passage ofcirculation fluid and is preferably internally fluted so that cuttingsand abrasives cannot become lodged between the stabilizer and themandrel and damage the stabilizer or the mandrel. The metallicreenforcement is mainly disposed within the diameters of the shouldersso that if occasion should require washing over the mandrel to recoverthe mandrel and the balance of the drilling string therebelow, therubber covering may be stripped down from the stabilizer and themetallic reenforcement will offer no serious impediment. 1

With the foregoing and other objects in View, which will be mademanifest in the following detailed description and specifically pointedout in the appended claims, reference is had to the accompanyingdrawings for an illustrative embodiment of the invention, wherein:

j Figure 1 is a vertical. section through a mandrel or drill collarillustrating a stabilizer embodying the present invention in appliedposition thereon. This view may be regarded as having been takensubstantially upon the line 1-1 upon Fig. 2;

Fig. 2 is a horizontal section taken substantially upon the line 2-2upon Fig. 1;

Fig. 3 is a partial view in vertical section taken substantially uponthe line 3-3 upon Fig. 1.

Referring to the accompanying drawings wherein similar referencecharacters designate'similar parts throughout, 10 indicates aconventional drill collar adapted to be incorporated in and form a partof a rotary well drilling string. This drill collar constitutes atubular mandrel and differs from the conventional drill collar merely inhaving its exterior reduced in diameter as indicated at 11 betweenshoulders 12 and 13. As will be observed from the drawing, the mandrelor drill collar 10-may be a single unitary structure in that it is notmade up of separate parts threaded or otherwise secured together.Consequently, despite the slight reduction in wall thickness between theshoulders 12 and 13 the mandrel may be adequately strong to resiststresses to which it may be subjected in the well.

The stabilizer consists of two opposed parts, generally indicated at 14and 15. These parts are preferably identical and are of generalsemi-cylindrical configuration so that they may be mutually assembledtogether about the mandrel between the shoulders 12 and 13. Each partconsists of a perforated metallic reenforcement 16 having a tongue 17 atone end and a socket 18 at the other that is complementary to the tongueso that it may receive the tongue of the opposed part. .The socket maybe formed of two opposed plates riveted as at 19 or otherwise secured toopposite sides of the reenforcement. In the tongues and sockets thereare apertures 20 that may be brought into mutual registration and theseapertures are tapped while the two opposed parts of the stabilizer arein assembled relationship so that the threaded portions in the socketsand in the tongues will properly align to receive tapered screws 21. Thescrews are preferably of the Allen set screw type. On the exteriors ofthe reenforcements 16 there are layers of rubber 22, and similarly onthe interiors of the reenforcements there are layers of rubber 23. Theselayers of rubber are bonded to the metal reenforcements and are mutuallyconnected through the perforations of the reenforcements. The maximumdiameter across the stabilizer is substantially equal to the gaugediameter of the bit that is being employed. It may be, however, a slightamount smaller so that the stabilizer will'not engage the walls of thewell with a tight fit in the event that the bit wears out of gauge. Theexternal layers 22 are vertically fluted as indicated at 24-to providefor 3. the flow of circulation fluid about the stabilizer. In a similarmanner, the internal layers 23 are vertically fluted as indicated at 25so that there will be grooves or; spaces between the stabilizer andthemandrel- 10. Li cuttings or abrasiveswork between the stabilizer andthe; mandrel these. cuttings or abrasives will work into the. grooves25: andmay be flushed out without damaging-either the mandrelor thestabilizer.

When it is desiredto: apply the stabilizer to the mandrel the two,opposed parts 14 and 15 are merely assembled: together about the mandrelbetween the shoulders Hand 13.. The. apertures are caused to align andthe set screws- 21 are driven in position. These set screws are disposedwell withinthe outside diameter across the stabilizer and are protectedthereby. If the stabilizer should become Worn or damaged and itisdesired to replace. the stabilizer, the set screws21 can be removed and.the parts 14 and 15 disassembled and replaced.

As will be noted from an inspection of Fig. l, the outside diameter ofthereenforcement 16. does not materially project beyond the diametersof, the shoulders 12 and 13.

Consequently, if at any time it should be necessary to wash over the,mandrel to recover a lost portion of the drilling. string the washovertool may merely telescope downwardly over the mandrel and strip theouter rubber layers 22 from the stabilizer. The metallic reenforcementat 16 being within the shoulders ofiers no impediment to such washoveroperations.

The sections of the stabilizer are not tightened or held in tightengagement withthe mandrel, it being the intention that the mandrelrotate within the stabilizer while the stabilizer may be frictionallyheld more or less stationary in the well. In the construction abovedescribed, a single-piece mandrel or drill collar may be employed ofadequate weight and strength, and the parts of the stabilizer can bemutually assembled about the mandrel between shoulders thereon which areintegral with the onc piece mandrel.

The term rubber" as herein used does not necessarily refer to naturalvulcanized rubber, but is intended to include synthetic rubbers andrubber-like compositions designed to withstand softening'under thetemperature and pressure conditions existing in the usual Well.

The constructions herein disclosed may have any one of a number ofdilferentstyles of clutches or releasable locksformed. between thebottom ofthe reenforcement of the stabilizer and the'mandrel 10.The-frictional engage- 'ment between the exterior of the stabilizer andthewa-lls of the: well normally holds such clutch or lock outofengagement so'that the mandrel can be rotated within the stabilizer.However, should the stabilizer become stuck in the well, on: lifting themandrel the stabilizer may be positively locked against rotationrelatively tothe mandrel andunder such circumstances, can be rotatedforcibly by the mandrel. Also, if occasion should require drillingdownwardly or milling over the mandrel the drilling tool or milling toolon engagement with the top of. the stabilizer will force. it downwardlyrelatively to the mandrel,.causing the clutch or lock to engage and thushold the stabilizer against rotation relatively to the mandrel. Suchlocks or clutches have not been illustrated herein as they haveheretofore been employed on drill pipe stabilizers.

Various changes may be made in the details of construction withoutdeparting from the spirit and scope of the invention as defined by theappended claims.

I claim:

1. A bit stabilizing means for rotary well'drilling strings comprising aone-piece drill collar section having its exterior of reduced diameterbetween upper and lower shoulders and having means at its ends providingfor its incorporation in. a rotary well drilling string, a stabilizerformed of two opposed semi-cylindrically shaped parts applicable to thereduced portion between thev shoulders and occupying substantially allof the: space between the shoulders, each of. said parts comprising asemi-cylindrical,

relatively stiff reenforcement having means at its side edges engageablewith the side edges of the reenforcement of the other part, said meanscomprising a tongue on the side edge of each reenforcement and a socketon the opposed side edge of the opposed reenforcement in which thetongue is receivable, there being apertures in each tongue and socketadapted to register with each other and which are arranged radially ofthe drill collar section, and screws receivable in said registeringapertures and layers. of rubber on the interior and exterior of thereentorcement, the exterior layer being of greater external diameterthan the maximum diameter of the drill collar section and the interiordiameter of the inner layer being such that the stabilizer is freetorotate on the drill collar section between the shoulders as a cylinder.

2. A. bit stabilizing means for rotary well drilling strings comprisinga one-piece drill collar section having its exterior of reduced diameterbetween upper and lower shoulders and having means at its ends providingfor its incorporation in arotary well drilling string, a stabilizerformed of two opposed semi-cylindrically shaped parts applicable to thereduced portion between the shoulders and occupying substantially all ofthe space between the shoulders, each of said parts comprising asemi-cylindrical, relatively stiff reenforcement having means at itsside edges engageable with the side edges of the reenforcement of theother'part, said means comprising a tongue on the side edge of eachreenforcement and a socket on the opposed side edge of the opposedreenforcement in which the tongue is receivable, there being aperturesin each tongue and socket adapted to register with each other and whichare arranged, radially of the drill collar section, screws receivable insaid registering apertures, and layers of rubber on the interior andexterior of the reenforcement, the exteriorlayer being of greaterexternal diameter than themaximum diameter of the drill collar sectionand the interior diameter of the inner layer being such that thestabilizer is free to rotate on the drill collar section between theshoulders as a cylinder, the exterior and interior surfaces of thestabilizer being vertically fluted.

3. A- bit stabilizing means for rotary well drilling strings comprisinga one-piece drill collar section having its exterior of reduced diameterbetween upper and lower shoulders and having means at its endsprovidingfor its incorporation in a rotary well drilling string, a stabilizerformed of two opposed semi-cylindrioally shaped parts applicable to thereduced portion between the shoulders and occupying substantially all ofthe space between the shoulders, eachof said'parts comprising asemi-cylindrical, relatively stiff reenforcement having means at itsside edges engageable with the side edges of the reenforcement of theother part, said means comprising a tongue on the side edge of-eachreenforcement and a socket on the opposed side edge of the opposedreenforcement inwhich the tongue is receivable, there being apertures ineach tongue and socket adapted to register with each other and which arearranged radially of the drill collarsection, screwsreceivable in saidregistering apertures, and layers of rubber on the interior and exteriorof the reenforcement, the exterior layer being; of greater externaldiameter than the, maximum diameter of the drill collar section and theinterior diameter of the inner layer being such that the stabilizerisfree to rotate on the drill collar section between the shoulders as acylinder, the exterior and interior surfaces of the stabilizer beingvertically fluted, the diameter of the reenforcement being no greaterthan the maximum diameter of the drill collar section.

4". A bit stabilizer comprising twosemi-cylindrical parts adapted'to' beassembled about a mandrel incorporatedin a: drilling: string, each partcomprising a semi-cylindrical metallic reenforcement having acircumferentially extending tongue at one end and a complementarycircumferentially' open. socket adjacent the other adapted to receivethe tongue of the other part, there being radially arranged aperturesin,the'tongues: and sockets adapted to register when the tongues are in thesockets, screws receivable in the aperatures, and layers of verticallyfluted rubber on the inside and outside of the reenforcement, the outerlayer extending radially outward beyond the tongues and sockets andscrews and the inner layer extending radially inward beyond the tongues,sockets and screws.

5. A bit stabilizer comprising two semi-cylindrical parts adapted to beassembled about a mandrel incorporated in a drilling string, each partcomprising a semi-cylindrical metallic reenforcement having portions atthe sides thereof disposed in overlapping relation to portions of theother part, there being radially arranged apertures in the overlappingportions of said parts adapted to register, radially arranged threadedfasteners receivable in the apertures, and layers of vertically flutedrubber on the inside and outside of the reenforcement, the outer layerextending radially outward beyond the threaded fasteners and the innerlayer extending radially inward beyond the inner ends of the threadedfasteners.

References Cited in the file of this patent UNITED STATES PATENTS DennieNov. 29, 1932 Osborne May 23, 1933 Williams July 10, 1934 Holt et a1 May28, 1935 Moffitt June 11, 1935 Miller Aug. 9, 1938 Kellegrew Oct. 24,1939 Smith Apr. 16, 1940 Fabrin Oct. 29, 1940 Smith Aug. 5, 1941 Brownet a1 Oct. 23, 1951 Medearis Apr. 28, 1953 Scott et al. June 2, 1953Williams et al Oct. 27, 1953

